Influence of the ambient humidity on the concentration of natural deposition-mode ice-nucleating particles

LOPEZ M.L.; AVILA E. E.

ATMOSPHERIC CHEMISTRY AND PHYSICS

COPERNICUS PUBLICATIONS

Lugar: Gottingen; Año: 2016 vol. 16 p. 927 - 932

1680-7316

This study reports measurements of depositionmodeice-nucleating particle (INP) concentrations at groundlevel during the period July?December 2014 in Córdoba,Argentina. Ambient air was sampled into a cloud chamberwhere the INP concentration was measured at a temperatureof 􀀀25 C and a 15% supersaturation over ice. Measurementswere performed on days with different thermodynamicconditions, including rainy days. The effect of the relative humidityat ground level (RHamb) on the INP concentration wasanalyzed. The number of INPs activated varied from 1 L􀀀1 atRHamb of 25% to 30 L􀀀1 at RHamb of 90 %. In general, a lineartrend between the INP concentration and the RHamb wasfound, suggesting that this variability must be related to theeffectiveness of the aerosols acting as INPs. From the backwardtrajectories analysis, it was found that the link betweenINP concentration and RHamb is independent of the origin ofthe air masses. The role of biological INPs and nucleationoccurring in pores and cavities was discussed as a possiblemechanism to explain the increase of the INP concentrationduring high ambient relative humidity events. This work providesvaluable measurements of deposition-mode INP concentrationsfrom the Southern Hemisphere where INP dataare sparse so far